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HI EricTheCarGuy:
So here’s the issue with the heater core – I got no heat in my car. Why do I think it’s the core? here’s my non-scientific approach to it. I took a heat gun thermometer and measured the temperature of:
1. The inlet hose before the valve (reading of about 74 Celsius or 165 F)
2. The inlet hose after the valve (reading of about 74 Celsius or 165 F)
3. The return hose (reading of about 44 Celsius or 110 F)Now I know there would be some heat loss since the heater core is like a radiator and a fan blows through it effectively cooling it down, but the difference in temperature isn’t felt inside the cabin. The fan works and blows air through. So the other possibility is the doors and flaps inside the heater unit. According to visual test or the moving parts near the glove compartment, everything seems to be working as expected. I don’t see or smell any coolant. In addition, the level of coolant remains the same; so chances of leaks are low.
Fortunately, the winter hasn’t been that bad, but I’m at the crossroads now – I’m doing some work on the suspension and it’s a lot easier to get at hoses (the return one at least). So it made me wonder, should I attempt a flush? or should I just go directly and replace the heater core?
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A 55F difference sounds high. It would be worth trying to flush it out. If the hoses allow, you can also switch the hoses around to reverse the flow. Possibly working away at the restriction over the summer.
Whether you go ahead and just replace the core is relative to how deep it’s buried in the dash. Most modern cars, the core is buried pretty deep so a flush is usually attempted first. As removal of the core usually requires complete dash removal and discharging of the AC.
SUCCESS!!!!
Thanks to the un-cooperating weather, I finally got around to do this, and yes I started with a heater core flush. I watched the video https://www.youtube.com/watch?v=dcL_0TWeZJY several times and finally I did it.
Due to the awkward location of hoses, I did improvise with extensions and my throttle control was a valve (images attached) – that way no mess and coolant in my face.
The flushing flushed debree, some of them were sizable which might have clogged the heater and hence the reason for the drastic temperature readings I took earlier on. I also did the CLR cleanse; and I decided to blow air in both directions – just to ensure free passage.
After throwing in coolant today and running the procedure as explained here https://www.youtube.com/watch?v=zUpXgAJ1gjU three times, I don’t think there’s any air in the system now. The gauge is where it’s supposed to be during all the three tries; and internally, the fan blows heat at 50 Celsius (120 F).
Tooaasstty!!!
I’m glad you got it sorted. In my experience however, Honda heater cores don’t often clog up. I would have recommended you start with bleeding the cooling system as that is the #1 cause of a no heat situation, especially with Honda’s. More on that here.
http://www.ericthecarguy.com/faq/solving-automotive-hvac-problems
Thanks for the updates and for using the ETCG forum.
I see that I got way too excited from the newly discovered heat that I forgot to write the other pat of the story.
So the cooling system forced me to flush it – as soon as I disconnected the return hose from the engine block, the coolant started flowing from the block area. Then, I opened up the petcock and cap and drained the rest. So there’s new coolant in.
I wish I had taken a picture, but after the first compressor blow job (the one where I clean the heater core with air), there was a small fragments – dirt as well as a small rusted metal piece. How did those get there (especially the shrapnel)? I don’t know.
I checked the reservoir and it was full of sludge. Needless to say, I cleaned that to the best of my abilities and the abilities of the chemical rad cleaner so at least I’m not pumping sludge that can potentially accumulate somewhere and cause additional blockages.
When I flushed the system – both from rad and heater core – the coolant was still green in colour so I’m assuming the ‘passageways’ should be in fairly decent shape.
As a precaution, now that it’s not winter, I may run the heat for the first 5 to 10 minutes of driving just to move all the fluids and see if heat loss is observed.
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